CONTENTS xi 



CHAPTER XVII 



PAGE 



The Mystery of the Cell . . . . -335 



CHAPTER XVIII 



The Elements and Water, in Relation to the Life- 

 World . . . . . . .355 



CHAPTER XIX 



Is Nature Cruel? The Purpose and Limitations of 



Pain ....... 3 6 9 



CHAPTER XX 



Infinite Variety the Law of the Universe — Conclu- 

 sion . . . . . .385 



INDEX . . . . . . .401 



